1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate by using plasma and a manufacturing method of a semiconductor device.
2. Description of the Related Art
In a semiconductor logic device and a DRAM device, etc, for example, a metal nitride film (simply called a titanium nitride (TiN) film hereafter) containing titanium nitride is used as materials of an electrode and wiring, etc, for inhibiting an increase of an electric resistance associated with microfabrication of the device. The metal nitride film can be formed by, for example, Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD). Titanium tetrachloride (TiCl4) gas containing chlorine is used as a precursor gas, to form the titanium nitride film by such methods. For example, patent document 1 describes a method of forming the titanium nitride film.    (Patent document 1) WO/2007/020874 Pamphlet
However, after study of the inventors of the present invention, it is found that when the titanium nitride film is formed by the aforementioned method, impurities such as chlorine atoms and carbon atoms are remained in a film. Particularly, when the titanium tetrachloride is used as the precursor gas, residue of the chlorine atoms in the titanium nitride film is remarkable. The residue of the chlorine atoms and carbon atoms causes the electric resistance of the titanium nitride film to be increased.
The chlorine atoms can be removed by forming the titanium nitride film at a high temperature or by carrying out high heat treatment after the titanium nitride film is formed. However, for example, when the high heat treatment is applied to the titanium nitride film formed as an upper electrode and a lower electrode of a capacitor of DRAM, characteristics of a capacitor insulating film sandwiched between titanium nitride films is deteriorated and a leak current is increased in some cases. Further, diffusion occurs in a source region and a drain region which are previously formed in the substrate, thus deteriorating the circuit characteristics and reducing a performance of a semiconductor device in some cases. Meanwhile, when the chlorine atoms are removed in a temperature range in which the deterioration of the aforementioned characteristics and diffusion are not generated, it is difficult to sufficiently remove the residual chlorine.
Further, the surface of the titanium nitride is naturally oxidized in a state of a layer containing lots of oxygen atoms. The electric resistance of the titanium nitride film is increased by the oxygen atoms remained in the titanium nitride film. Also, interfacial characteristics between the titanium nitride film and the capacitor insulating film, etc, formed thereon are changed and device characteristics are deteriorated.
Further, when the upper electrode and the lower electrode of the DRAM are formed by the titanium nitride film, the metal oxide film, etc, being the capacitor insulating film, is formed after the titanium nitride film, being the lower electrode, is formed. However, when the metal oxide film is formed, the titanium nitride film, being the lower electrode, is oxidized, and the device characteristics are deteriorated in some cases.